The invention relates to the structure of a rotary sensor particularly suitable for the wheel sensor of a vehicle.
A rotary sensor of the sort disclosed by Japanese Patent No. 63-285414 is known. According to the disclosed patent, the sensor is composed of a stay mounted on a vehicle with a case mounted on said stay and containing sensor elements such as a pole piece, and a bobbin etc. mounted on said stay. The sensor elements such as the pole piece and bobbin etc. are fixed in a molded resin case, and the case is fixed to the stay by pressing the case into a hole in the stay, and the molded resin case is formed by the unification of both case and a body.
The difficulties with this sensor are 1) that the assembly work of the whole wheel sensor is very complicated due to the difficulty of installing sensor elements such as the poll piece and the bobbin etc. in the case, and 2) that the high machining accuracy is required for the poll piece and the case to prevent water penetration through the tolerated gap between the pole piece and the case, because no particular device for water proofing the tolerated gap is provided.